Well cleaning apparatus

ABSTRACT

An apparatus for cleaning a well and removing particle incrustation from a well screen, and a method of using the apparatus, is disclosed. The apparatus and method utilize a source of high pressure gas to air lift well liquid and particles to the ground surface, and simultaneously apply a high pressure fluid to the well screen inner surface to dislodge particles, wherein the volume of well liquid removed is greater than the volume of high pressure fluid injected into the well.

United States Patent 1191.

'Henrich [4 Dec. 10, 1974 [5 1 WELL CLEANING APPARATUS 2,518,591 8/1950 Aston et al. 1751213 x 2,720,381 10/1955 Quick 175/205 X [75] invent Edward Mound 3,153,290 10/1964 Saito 175/215 x [73] Assignee: Bergeson-Caswell, Inc., Minnetonka,

Minn. Primary Examiner-David H. Brown [22] Filed: Man 1, 1973 Attorney, Agent, or Firm-11. Dale Palmatier; James R. Haller [21] Appl. No.: 336,975

. [57] ABSTRACT (g1. 166/22l.332,11b 62/73 (1) (2] An apparatus for cleaning a we and removing Pam Fieid 312 1 cle incrustation from a well screen, and a method of 0 a c l75/67 using the apparatus, is disclosed. The apparatus and method utilize a source of high pressure gas to air lift well liquid and particles to the ground surface, and si- [56] References Cited multaneously apply a high pressure fluid to the well UNITED STATES PATENTS screen inner surface to dislodge particles, wherein the 587,126 7/1897 McAdams.. 175/213 volume of well liquid removed is greater than the vol- 722,764 3/1903 :teen ume of high pressure fluid injectedinto the well. 1,853,379 4 1932 otino 175/205 2,019,719 11/1935 Miller 175/205 7 Claims, 5 Drawing Figures 1 WELL CLEANING APPARATUS WELL CLEANING APPARATUS AND METHOD fmethod ard practiced within a well, and eliminate the necessity for removing the well screen and casing pipe to which it is attached from the interior of the well hole for cleaning and restoration. The invention conserves both time and expense, and achieves an improved result, in the cleaning of well screens andrestoring of the well to its maximum operating capacity. The embodiment of the invention described herein is preferably applicable to water wells, although other types of liquid wells are also adaptable to the invention. Reference herein will be made to water when describing the normal content of a well, it being understood that other types of liquidwells are included within the scope of the invention.

There are at least two reasons why a well loses productivity and efflciency from a reduction of water flow into the well from the surrounding soil: the well screen can become clogged or incrusted, or the region of formation or soil outside of and adjacent the well screen can become densely packed with fine material and 7 thereby prevent ground water from reaching the well screen. The process of bringing a well to its maximum efficient yield of water is referred to as development" of the well. The process involves the removal of fine particulates, known as fines, from the natural soil or formation outside of the well screen. On a newly constructed well, the well screen commonly has slot openings allowing from to 60 percent of the natural surrounding formation to pass the screen. Removal of this fine material, and the simultaneous grading of the remaining material adjacent to the screen so that the coarser material lays closest to the screen, is the essential process of development. The end result of adequate development is increased permeability and hence reduced friction loss to the water as it enters the well so that the well is at maximum productive efficiency.

tation must also be removed if the well is to be returned to its original productivity.

Briefly, this invention includes apparatus for directing a high pressure fluid jet at the interior surface of the well screen, thereby removing incrustation and dislodging particulates from within the well screen and in the region immediately adjacent to and exterior of the well screen. The liquid jet is applied in combination with a high pressure gas which is injected into thewell at a point near the bottom. The high pressure gas, typically air, generates rising gas bubbles which lift water within the well to the ground surface in considerable volume. The application of high pressure gas to the bottom portion of the well utilizes the principle of air lifting, known in the art, and in combination with the liquid jet application results in a significant improvement to the development process. The inventive apparatus comprises a first pipe for removing water from the well according to the principle of air lifting, a second pipe for injecting a high pressure gas, such as air, to the bottom of the well, and a third pipe for admitting a high pressure fluid via a jet nozzle and directing the fluid jet to the interior surface of the well screen. The inventive method comprises the novel steps practiced in the development process described herein.

A further problem related to the development and redevelopment of wells is the normal stratification of soil formations along the length of any well hole. Soil formations are typically not uniform in sieve analysis, even throughout the length of a well screen. There may be layers of variable thickness from as little as several inches of depth, and such layers may comprise fine or coarse material, or mixtures thereof. During the development process, each'such layer requires a longer or shorter time time of development to optimally restore the well screen efficiency in that layer. Another novel aspect of the present invention is that the method of implementing the invention enables the operator to measure and observe the removed particulates, and therefore to gauge the relative efficiency at which a particular level or depth of well screen is operating. This enables the operator to concentrate the development process at well screen depths that are most in .need of it.

Yet another advantage of the present invention is that the fines" removed from the well are automatically pumped to the surface of the ground, and are not permitted to settle at the bottom'of the well. This removal of fines eliminates any necessity for subsequent bailing of the well, which might be needed to remove sediment.

Further advantages and novel features of this invention will become apparentfrom a reading of the following specification and claims, together with the appendeddrawings, in which:

FIG. 1A illustrates theapparatus forming a part of the invention which is located on the surface of the ground over the well;

FIG. 18 illustrates an embodiment of the inventive apparatus which is submerged within the well;

FIG. 2 shows a preferred embodiment of the inventive apparatus which is submerged within the well;

FIG.3 is a partial elevational view of the apparatus of FIG. 2;

FIG. 4 shows atop plan view of the apparatus of FIG. 2 and the surrounding well screen.

Referring first to FIG. 1A, the apparatus is shown which normally is positioned over a well hole on the surface of the ground. This apparatus is connected to various devices common in the art, such as a high pressure air source, a high pressure fluid source, and supportive apparatus for suspending the assembly of FIG. 1A over the well hole. One skilled in the art will readily have the knowledge to select appropriate ones of these available devices for connection to the apparatus of FIG. IA, especially in light of the specification herein.

The apparatus of FIG. 1A is suspended from a suitable 7 well rigging by means of cables 15. The rigging has the fittings 19. Drain hose 20 is coupled to a storage tank (not shown) or other suitable drainage means. An air hose 21 is connected to air pipe 17 through suitable valving, air pipe 17 being located within eduction pipe 14. The top end of eduction pipe 14 is sealed by cover .22, which has a hole at its center to provide for the passage of air pipe 17. The other end of air hose 21 is connected to a source of high pressure air (not shown), such as a compressed air tank and delivery system of a type commonly known in the art.

Also clamped to support bracket 16 is high pressure fluid pipe 24. The top end of fluid pipe 24 is connected by means of coupling 25 to a high pressure line 26. This high pressure line 26 is connected to a source of high pressure fluid (not shown). Typically, the high pressure fluid source comprises a high pressure water tank and associated delivery system. The entire apparatus shown in FIG. 1A is suspended above a well hole, and eduction pipe 14, air pipe 17, and fluid pipe 24 extend downwardly into the well. The lower end of air pipe 17 is located well below the natural level of the water in the well; at least half, and preferably more than half, of

the length of the air pipe 17 is submerged in the water of the well below the natural water level. Eduction pipe 14 is also submerged below the natural water level, and

' fluid pipe 24 extends downwardly to the vicinity of the well screen and is terminated in a high pressure nozzle to be hereinafter described. When air is forced under pressure down air pipe 17 into the water in the eduction pipe 14, the rising air bubbles carry water and particles with them, and the water and particles are carried to the surface without mechanical pumping.

FIG. 1B illustrates the inventive apparatus which is submerged within the well in the vicinity' of the well screen. Eduction pipe 14 is connected via a reducer coupling 27 to an open-ended section of eduction pipe 28. Pipe 28 has an open 28a into which water and particles can be drawn and air-lifted to the surface as previ- .hose by means of tee connection 18 and other pipe quantity of water supplied through nozzle 29, so that water is actually being removed from the formation around the well as the well is being cleaned. The entire assembly can be rotated within the well to allow nozzle 29 to direct its fluid jet around the entire inner circumference of the well. When the incrustation particles have been removed sufficiently from a first circumferential zone the entire assembly may be raised or lowered by means of cables 15 to enable cleaning ofa sec ond circumferential zone. This process eventually allows the entire well screen and surrounding formation to be cleaned.

FIG. 2 .illustrates another, and preferred, embodiment of the apparatus located within the well. In this embodiment eduction pipe 14 and air pipe 17 remain stationary in a location near the bottom of the well during the entire well screen cleaning operation. Fluid pipe 24 is slidably attached to the outside of eduction pipe 14 by means of housing 35, which has an upper and lower collar 36 designedto loosely fit around eduction pipe 14. The assembly consisting of fluid pipe 24, housing 35, and collars 36 can be raised or lowered independently of eduction pipe 14 and air pipe 17. With this construction nozzle 29 can direct a fluid jet at aparticular well screen circumferential depth while the open end 14a of the eduction pipe remains close to the bottom of the well. This enables encrustation particles to be drawn into open end 14a and air lifted to the surface, said encrustation particles originating at any and all well screen depths. Because this embodiment allows all the encrustation particles to be collected and carried out of the well as the cleaning job progresses it enables the operator to make a determination of the degree of cleaning, by merely examining the outflow from the eduction pipe. For example, if the operator observed a reductionin particles in the eduction pipe outflow he can assume that the well has been cleaned at the particular nozzle depth he is operating. He can therefore adjust the nozzle depth by raising or lowering housing 35 to select another depth within the well for cleaning. This method of operation is particularly useful in wells having strata of soil formations which contain varying degrees of fines, FIG. 2 pictorially illustrates an example of a soil level 38 which differs in degree of coarseness from neighboring soil strata. Such a soil strata may require a greater or lesser degree of ously described. Air pipe 17 is shown extending downwardly near the vicinity of open end 28a. Fluid pipe 24 is also shown in FIG. 18; it terminates in a high pressure nozzle 29 designed to direct a fluid jet at generally right angles to the direction of fluid pipe 24. This fluid jet strikes the inner surface of well screen 23, dislodging incrustation particles from the well screen and the surrounding region. FIG. 1B pictorially illustrates a zone 30 immediately surrounding well screen 23, which zone includes the region where fines are accumulated to generally 'lower the efficiency of the well. Eduction pipe 28 and nozzle 29 are held in a fixed relationship by means of bracket 31, which generally strengthens the apparatus located within the well.

The combination of air pipe 17 and eduction pipes 28 and 14 acts to remove a significant quantity of water and particles from the well. At the same time as this action occurs, fluid pipe 24 carries a volume of high pressure fluid to be ejected through nozzle 29. It is necessary that the guantity of water lifted to the surface through eduction pipes 28 and 14 be greater than the cleaning and therefore require a greater or lesser application of high pressure fluid through nozzle 29. The apparatus of FIG. 2 enables the operator to deal with situations of this type, and a trained operator can detect changes in the soil strata by merely observing the outflow from eduction pipe 14.

FIG. 3 illustrates in enlarged view the apparatus connected to housing 35. Collars 36 are attached at the upper and lower ends of housing 35 and encompass the eduction pipe. A rigid annular bar 39 is connected to collar 36 by struts 40; an L-bracket is welded between annular bar 39 and one of the collars 36. L-bracket '41 provides a mounting base-to which the closed bottom end of fluid pipe 24 can be bolted so as to hold nozzle 29 in a fixed relationship with housing 35. Fluid pipe 24 is also rigidly attached to the second collar 36 by means of bracket 42. With these connections the entire assembly consisting of housing 35, fluid pipe 24, and nozzle 29 can be rotated around eduction pipe 14 and guided along eduction pipe 14. This arrangement permits the nozzle 29 to be operated at various elevations and with- 4 out requiring major disassembly of the eduction pipe 14 and air pipe 17 at the top of the well.

FIG. 4 illustrates'a top sectional view taken at lines 4-4 in FIG. 2. This figure shows the relationship of the various components within the well screen. In particular, it illustrates annular bar 39 concentrically positioned within well screen, and collar 36 encompassing eduction pipe 14. Fluid pipe 24 is rigidly attached to collar 36 by means of bracket 42; struts 40 rigidly connect collar 36 to annular bar 39. This construction provides an adequate and economical interconnection of the various elements of the invention, but other similar constructions would also be useful to accomplish the intended purpose of the invention. water from the nozzle will cause some damage to the screen. The bracket plate 31 which is substantially circular in shape, will maintain the nozzle 29 in spaced relation from the screen at all times. The off center position of the nozzle sembly in the well.

Although the open end 28a of the eduction pipe 28 moves upwardly and downwardly along the wall screen during the cleaning operation, some of the particles of incrustation and other materials loosened by the jet stream will move with the water into the end of the eduction pipe so that the discharge of these particles can be monitored to permit the operator to observe the particles and obtain information as to the nature of the formation and incrustation at the various levels of the well.

I claim:

1. Apparatus for cleaning a well and well screen,

comprising:

a. an eduction pipe'disposed within said well and having an open end positioned along said well screen length; 1

'b. a gas pipe disposed within said eduction pipe and I having at least one-half its length immersed beneath the normal liquid surface of said well, and having an open submerged end within the eduction pipe and above the open lower end of the latter;

0. a high pressure fluid pipe disposed within said well and adjacent but outside said eduction pipe, said fluid pipe having a jet nozzle positioned along said well screen length and at an angle to direct a jet stream of fluid against said well screen to dislodge fine particles;

d. drain means connected to said eduction pipe for conveying fluid away from said well;

e. means for conveying a high pressure gas into said gas pipe to cause air-lifting of water and entrained fine particles through the eduction pipe; and

f. means for delivering a high pressure fluid into said fluid pipe.

2. Apparatus as claimed in claim 1, further comprising a housing rigidly mounted to the high pressure fluid pipe and rotatably mounted to the eduction pipe, and

I enabling the housing and fluid pipe to be rotated about the eduction pipe to cause said jet nozzle to direct a jet stream of fluid at all circumferential positions within said well.

lected elevations within said well connected to said third pipe.

4. Apparatus as claimed in claim 3 wherein said housing includes a first and second collar slidably encompassing said first pipe and having bracket means for rigidly attaching said third pipe to said collars.

5. Apparatus for unclogging a submerged well screen and surrounding region in a well, comprising:

a. an eduction pipe having an open end positioned near the bottom of said well and having its other end in communication with the surface of said well;

b. a high pressure air pipe disposed within said eduction pipe and having an open positioned adjacent but above the open end of said eduction pipe, and means for connecting the air pipe to a source of compressed air;

c. a housing slidably attached to said eduction pipe;

d. a jet nozzle attached to said housing and directed toward said well screen, and means for connecting the jet nozzle to a source of high pressure fluid; and

e. positioning means, connected to said housing and extending to the surface of said well, for varying the elevation and rotational position of said housmg. g

6. Appartus as claimed in claim 5, wherein said housing further comprises a first collar encompassing said eduction pipe and rigidly attached to the jet nozzle an annular bar of diameter less than said well screen, attached to said first collar; and a second collar encompassing said eduction pipe, and attached to said annular bar, wherein said annular bar is approximately intermediate said first and second collar.

7. Apparatus for cleaning a well and unclogging a submerged well screen and surrounding region in a well, comprising:

a. an air pipe submerged in the well, wherein more than one-half the length of said air pipe is immersed in well liquid andthe bottom end of said pipe is open, and means for connecting the air pipe to a source of high pressure air; 7

b. an open-ended eduction pipe of diameter at least several times that of said air pipe and of length at least several feet longer than said air pipe and extending below the bottom end of the air pipe, said eduction pipe fitted concentrically around said air pipe and having a drain connection at the ground surface of the well to convey well liquid away from said well;

c. a high pressure water pipe extending into said well to a region including said well screen, said high pressure water pipe being positioned adjacent but outside said eduction pipe in said well and including means for connecting the high pressure water pipe to source of water under high pressure;

d. a high pressure jet nozzle connected to the bottom end of said high pressure pipe, and directed toward the inner surface of said well screen;

e. a housing rigidly attached to said high pressure water pipe, and having a pair of collars encompassing said eduction pipe but of inner diameter larger than the outer diameter of said eduction pipe, and having an annular bar of diameter less than said well screen diameter; and

. a supporting means allowing changing of the elevational and rotational position of said high pressure water pipe, said supporting means located at the ground surface of said well and attached to said high pressure pipe and being capable of both elevational and rotational movement. 

1. Apparatus for cleaning a well and well screen, comprising: a. an eduction pipe disposed within said well and having an open end positioned along said well screen length; b. a gas pipe disposed within said eduction pipe and having at least one-half its length immersed beneath the normal liquid surface of said well, and having an open submerged end within the eduction pipe and above the open lower end of the latter; c. a high pressure fluid pipe disposed within said well and adjacent but outside said eduction pipe, said fluid pipe having a jet nozzle positioned along said well screen length and at an angle to direct a jet stream of fluid against said well screen to dislodge fine particles; d. drain means connected to said eduction pipe for conveying fluid away from said well; e. means for conveying a high pressure gas into said gas pipe to cause air-lifting of water and entrained fine particles through the eduction pipe; and f. means for delivering a high pressure fluid into said fluid pipe.
 2. Apparatus as claimed in claim 1, further comprising a housing rigidly mounted to the high pressure fluid pipe and rotatably mounted to the eduction pipe, and enabling the housing and fluid pipe to be rotated about the eduction pipe to cause said jet nozzle to direct a jet stream of fluid at all circumferential positions within said well.
 3. Apparatus as claimed in claim 2, further comprising means for raising and lowering said jet nozzle to selected elevations within said well connected to said third pipe.
 4. Apparatus as claimed in claim 3 wherein said housing includes a first and second collar slidably encompassing said first pipe and having bracket means for rigidly attaching said third pipe to said collars.
 5. Apparatus for unclogging a submerged well screen and surrounding region in a well, comprising: a. an eduction pipe having an open end positioned near the bottom of said well and having its other end in communication with the surface of said well; b. a high pressure air pipe disposed within said eduction pipe and having an open positioned adjacent but above the open end of said eduction pipe, and means for connecting the air pipe to a source of compressed air; c. a housing slidably attached to said eduction pipe; d. a jet nozzle attached to said housing and directed toward said well screen, and means for connecting the jet nozzle to a source of high pressure fluid; and e. positioning means, connected to said housing and extending to the surface of said well, for varying the elevation and rotational position of said housing.
 6. Appartus as claimed in claim 5, wherein said housing further comprises a first collar encompassing said eduction pipe and rigidly attached to the jet nozzle an annular bar of diameter less than said well screen, attached to said first collar; and a second collar encompassing said eduction pipe, and attached to said annular bar, wherein said annular bar is approxImately intermediate said first and second collar.
 7. Apparatus for cleaning a well and unclogging a submerged well screen and surrounding region in a well, comprising: a. an air pipe submerged in the well, wherein more than one-half the length of said air pipe is immersed in well liquid and the bottom end of said pipe is open, and means for connecting the air pipe to a source of high pressure air; b. an open-ended eduction pipe of diameter at least several times that of said air pipe and of length at least several feet longer than said air pipe and extending below the bottom end of the air pipe, said eduction pipe fitted concentrically around said air pipe and having a drain connection at the ground surface of the well to convey well liquid away from said well; c. a high pressure water pipe extending into said well to a region including said well screen, said high pressure water pipe being positioned adjacent but outside said eduction pipe in said well and including means for connecting the high pressure water pipe to source of water under high pressure; d. a high pressure jet nozzle connected to the bottom end of said high pressure pipe, and directed toward the inner surface of said well screen; e. a housing rigidly attached to said high pressure water pipe, and having a pair of collars encompassing said eduction pipe but of inner diameter larger than the outer diameter of said eduction pipe, and having an annular bar of diameter less than said well screen diameter; and f. a supporting means allowing changing of the elevational and rotational position of said high pressure water pipe, said supporting means located at the ground surface of said well and attached to said high pressure pipe and being capable of both elevational and rotational movement. 